JPH1062303A - Device for measuring luminous intensity and chromaticity of object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute a precise analysis at high speed by combining a lens for generating a Fourier transformation and a field lens with the circular aperture of a diaphragm to select an elliptic measuring area on an object to be analyzed. SOLUTION: A measurement lens 2 generates the Fourier transformation (angle intensity distribution) 102 of the unit area 101 of an object 1 within an image focal plane Fi. A transfer lens 3 forms the image of the distribution 102 on a sensor 4 formed of one set of detectors 4i, j. Each detector 4i, j outputs electric signals Si, j, ϕcorresponding to the luminous intensity of the area 101 to a processing circuit. A field lens 10 is provided on the lens 3 side of the focal plane Fi, and a lens 10 is combined with the lens 2, these are combined with a circular aperture of the diameter regulated by a diaphragm 4. Thus, to a beam having an incident angle γ and an azimuth ϕ, an elliptic measuring area is selected on the object 1. Thus, a precise analysis can be performed at high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for judging characteristics of a unit area of an object in an observation direction of the unit area.
The invention relates to a device for measuring the luminosity and chromaticity of an object, in particular a liquid crystal screen. The apparatus includes a measurement lens that generates a Fourier transform (angular intensity distribution) of a unit area in an image focal plane, and a transfer lens that forms an image of the distribution on a sensor including a set of detectors, Each detector is a transfer lens that generates an electric signal corresponding to the luminous intensity of the unit area for a given angular coordinate, an aperture that exists on the optical path of the light beam to define the aperture of the unit area, and each detection cell of the sensor And a processing circuit for receiving an electrical signal from the device.

[0002]

BACKGROUND OF THE INVENTION Conoscopic methods and apparatus have been featured in a number of publications, particularly in French Patent Applications Nos. 870,944 and 9,500,118, Japanese Patent Publication No. 34858, and JP-A-5-288538. However, these known solutions raise various problems. That is, the gain of the system is strongly dependent on the angle, whether or not the sample under test is itself a light emitter.

For industrial production applications, the measurement must be fast.

The first disadvantage is easily explained by the fact that the analysis area is optically conjugate with the stop with respect to the measuring lens (Fr. Patent Application Nos. 870,944, 950).
0118 and JP-A-5-288638).

That is, although these analyzers used to determine the luminosity or chromaticity of a display screen, especially a liquid crystal display screen, are useful, their optical system is emitted from a unit area of an object to be analyzed. No consideration is given to the reduction of the cross section of the light beam. This is a function of the angle of inclination of the ray and, in fact, the angle θ with respect to the normal to the basic exit area of the object under analysis.
Varies in a ratio of 1: cos θ. The analyzed apparent area changes in a very wide range according to the analysis angle θ. Under these conditions, it is necessary to correct the analysis result, that is, to process the signal sent from the sensor using the corrected conditions. In practice, this involves the use of a wide range of means, especially in the form of computation, which complicates the equipment and significantly reduces the speed of analysis, and in particular, as the angle of incidence of the beam increases, the signal-to-noise ratio Decreases, the quality of the analysis result deteriorates.

It is an object of the present invention to remedy these disadvantages,
Light emission area that enables accurate analysis to be performed at high speed,
In particular, it is to create a device for analyzing the luminosity and chromaticity of a screen such as a liquid crystal screen operating in a transmission mode or a reflection mode.

[0007]

For this purpose, according to the invention, according to the invention, in a device of the kind described above, a field lens is combined with a lens for generating a Fourier transform, and
And the azimuth angle φ by combining two optical systems and a circular aperture having a diameter (d) defined by a stop.
Makes it possible to select an elliptical measurement area on the object to be analyzed for rays having
It has a short axis of about (D) and a long axis of about (D / cos θ), and the product of the short axis multiplied by the long axis changes by 1 / cos θ, and (D) and (d) show the measurement lens and Related to the device, characterized by the magnification of the optical system consisting of the field lens, said major axis being in a plane passing through the axis of the optical system and the ray of light exiting from the center of the elliptical region. .

Due to the design of the lens, the analyzer can release the signal derived from the cos θ coefficient (or the reciprocal of this coefficient), which depends on the angle of inclination of the analyzed light beam.

[0009] This shows that the analysis, which is collected directly by the sensor, preferably a charge-coupled device (CCD) sensor, is directly transmitted, so that the analysis is considerably simplified. Not only are these results directly available,
The signal-to-noise ratio is significantly improved as compared to the signals and results obtained using conventional devices.

According to another feature, the optical path of the light beam comprises a wavelength-selective filter, ie a filter or a polarization filter which is selective for a group of wavelengths. This enables, for example, selective analysis limited to wavelengths that can be sensed by the naked eye.

According to another characteristic, the optical path of the light beam is provided with a slit defining an analysis line, in particular an azimuth line.

According to its positioning, this slit is
Allows analysis of objects along a given azimuth line, thereby speeding up the analysis. In this case, the analysis is limited to the cell lines and not to the sensor cell matrix.

When the object is a luminous body, the analyzer receives light rays emitted from the object.

It is also useful to analyze the reflection characteristics of an object. To do this, it is necessary to illuminate the object accurately in order to enable a meaningful and reproducible analysis.

For this purpose, the device is in the image focal plane of the lens conjugate with the focal plane of the object, consists of controlled light-emitting elements, and has a constant cross section defined by the illumination diaphragm The analysis unit area of the object using many rays,
The lighting device includes a light source configured to illuminate via a lens.

[0016] Particularly preferably, the device comprises a translucent mirror for shifting the light source aside so that the analytic light emitted from the basic emission area of the object passes therethrough.

This analysis using the illumination of the object relates to the study of the reflection properties of the object, and furthermore to the study of the effects of unwanted illumination, for example, on the legibility of the object, which is generally a screen.

[0018]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

According to FIG. 1, the device according to the invention measures the luminosity and chromaticity of an object 1. Object 1 is
For example, a liquid crystal screen, whose characteristics are measured on a unit area including the entire object or a part thereof.

The device comprises a lens 2 on which the object 1 to be analyzed is placed. Next to this lens 2 is a transfer lens, which gives an image on the sensor 4 from a Fourier transform for a given angular coordinate in the plane Fi. The diaphragm 5 defines a circular aperture having a diameter of 3 and, in cooperation with the lens 2 and the field lens 10, defines a range of the basic emission area 101 on the object 1. Further, the aperture 5 is a lens 2
Light ray 100 emitted from the unit area 101 toward
And the angle θ formed by the ray with respect to the axis XX of the system.

The stop 5 is preferably located on the upstream side of the transfer lens 3, and a filter 8 for passing only a certain wavelength or only a certain group of wavelengths is disposed in front of the stop 5. This may be a polarizing filter.

Finally, the present apparatus may have a shutter 9 that can define the time during which the sensor 4 or its detection cells 4i, j are illuminated. Each cell receives the flux via the light beam 100 emitted from the unit area 101 of the object 1 in the direction θ.

The two main functions of the lens 2 are
In cooperation with 0 and the stop 5, it is to define a unit area 101 optically conjugate with the stop 5, and to transmit an image representing the angular distribution of light emitted from the object 1 into the plane Fi. The major axis of this elliptical unit region 101 lies in the plane of FIG. 1, and the minor axis is orthogonal to the plane of FIG.

More specifically, the lens 2 defines an elliptical unit area 101 whose short axis is approximately D and whose long axis is approximately D / cos θ.

Here, D is a conjugate measurement of the diameter d of the stop 5 by the optical system, and these two quantities are related by the magnification G.

More specifically, the elliptical unit area 10
The major axis of one is on a plane passing through the optical axis XX and a ray 100 passing through the center of the elliptical region 101 (this ray is included in the plane of FIG. 1).

Therefore, the focal plane Fi contains a plane image of the light intensity distribution emitted from the object 1.

The device is completed by a field lens 10, which gives a real image of the object 1 in the plane of the stop 5, so that the light rays can be stopped and, instead, a unit area 101 for analysis can be obtained. .

The image formed in the plane Fi is
And 3 to the sensor 4. Each detection cell 4i, j of the sensor 4 is provided with a light beam 10 emitted from the surface 101.
Directly coupled to the outgoing direction specified by the zero incident angle θ and the azimuthal angle φ.

When these angles change, the unit sensor receiving the light beam also changes.

Under these conditions, the sensor 4 is directly coupled to the signal Si, j, which is coupled to each elementary cell 4i, j of the sensor, ie to each angular position of the ray 100 emitted from the object 1. C that can collect signals Si, j
It is particularly advantageous to be a CD sensor.

FIG. 2 schematically shows this state.
The measuring device is the same as that of FIG. 1, but the cells 4i, j
(Θ ₁ , φ). . . 4i, j (θ ₄ , φ) and several rays 100 (θ ₁ , φ), 100 (θ ₂ , φ)
φ), 100 (θ ₃ , φ) and 100 (θ ₄ , φ) are merely added.

These cells of the sensor 4 send a series of signals, generally represented by the reference Si, j (θ _n , φ).

FIG. 2 shows a plane (azimuth angle φ) of FIG.
Ray 100 (θ _n , φ) having an axis in the plane corresponding to
Indicates that it necessarily converges to the cells 4i, j (θn, φ) of the sensor 4 which are also in the plane of FIG. 2, that is, arranged on a straight line segment.

FIGS. 1 and 2 are diagrams illustrating the use of a measuring device for analyzing a light beam having an angle θ emitted from an object 1. FIG.

In order to enable such an analysis, it is necessary that the object 1 is a luminous body or reflects incident light.

It is also useful to measure the optical response when the object 1 itself is a luminous body and receives external light.

FIG. 3 shows a device according to the invention, corresponding to the above, provided with means for illuminating the object 1.

In this figure, only the main elements of the apparatus used for lighting are shown. These elements have the same reference numerals as in the previous figures.

In order to illuminate the object 1 using the light ray 200 at the angular position (θ, φ), the present apparatus uses a line, for example, a line in a plane of the drawing, or a matrix (two-dimensional distribution). It consists of a lighting device constituted by a light source 11 comprising light emitting elements Li, j arranged. These light-emitting elements Li, j are controlled by a control device such as a microcomputer 7.
And processes the signal obtained from the signal Si, j (θ _n , φ) sent from.

As a result, the signal S sent from the sensor 4
As a function of the analysis program that appropriately considers the result extracted from i, j (θ _n , φ), it becomes possible to control the illumination of the unit area 101 or, more generally, the object 1.

The light source 11 is in the image focal plane of the lens 2 (taking into account the field lens 10).

In practice, the light source 11 is shifted to the side by using the translucent mirror 12 in order to leave a region around the optical axis XX of the present apparatus and to allow light rays emitted from the object 1 to pass freely.

The illuminating device further includes a lens 13 and a stop 14, and forms a convergent light beam within the image focal plane Fi of the lens 2, and collides with the unit area 101 at an angular position (θ, φ).
Are generated.

The angle of incidence θ is determined by the state of the controlled light emitting element Li, j that emits a light beam.

The stop 14 is a circular stop and can benefit from the optical reversibility of the lens 2 as described above in the case where the light rays emanating from the lens 2 are the light rays emanating from the object 1.

The angular position (θ, φ) for illuminating the unit area 101 is selected as a function of the analysis program to be executed. This program, for example, as described with respect to FIGS. 1 and 2, initially does not use a light source, and then uses a light source that emits a ray of angular position (θ, φ) with various angles θ _i . It consists of analyzing the object 1.
This angle can be changed during the analysis by the control circuit 7 using the various light emitting elements Li, j of the light source 11.

FIG. 4 schematically shows the illumination of the unit area 101 in different illumination directions, ie by activating another light-emitting element Li, j of the light source 11 to reproduce a given illumination distribution. Is shown in Each element shown in FIG. 4 is denoted by the same reference numeral as in each of the preceding figures.

[Brief description of the drawings]

FIG. 1 is a diagram showing a measuring apparatus according to the present invention together with a trajectory of a parallel ray emitted from a unit area of an object to be analyzed.

FIG. 2 shows the device of FIG. 1, but schematically showing various rays emitted at different angles from the same unit area of the object to be analyzed.

FIG. 3 schematically shows an apparatus for illuminating a unit area of an object to be analyzed.

FIG. 4 is a view similar to FIG. 3, showing a case where a unit area of an object is illuminated with various light rays having different incident angles with respect to the unit area of the object.

Claims (6)

[Claims] An object (1) for measuring the luminous intensity and chromaticity of a liquid crystal screen in order to determine the characteristics of a unit area (101) of the object (1) in an observation direction of the unit area (101). An apparatus, comprising: a Fourier transform (angular intensity distribution) of the unit area (101) in an image focal plane (Fi).
and a sensor (4) consisting of a set of detectors (4i, j).
A transfer lens for forming an image of this angular intensity distribution,
For each given angular coordinate, each of the detectors generates an electric signal (Si, j, j) corresponding to the luminosity of the unit area (101).
φ), a stop (5) existing on the optical path of the light beam for defining the aperture of the unit area (101), and the detection cells (4i, 4i, 4) of the sensor (4). j) a processing circuit (6) for receiving the electric signal from (j), wherein a lens (2) for generating a Fourier transform is combined with a field lens (10), and these two optical means (2, 10) ) And a circular aperture having a diameter (d) defined by the stop (5), an ellipse is formed on the object (1) to be analyzed with respect to a ray having an incident angle θ and an azimuth angle φ. This elliptical region has a minor axis of approximately (D) and approximately (D /
cos θ), and the product of the short axis multiplied by the long axis changes by 1 / cos θ, and the magnitudes (D) and (d) are determined by the measurement lens (2) and the field lens ( 10), the major axis being the axis of the optical system and the elliptical region (10).
1) An apparatus characterized by being on a plane passing through light rays of an angle (θ) emitted from the center of 1). 2. The device according to claim 1, wherein the optical path of the light beam comprises a wavelength-selective filter, or a filter or a polarization filter that is selective for a group of wavelengths. 3. The device according to claim 1, wherein the optical path of the light beam is provided with a slit defining an analysis line of an angle, in particular an azimuth line. 4. The object (1) using a light beam which is in a conjugate plane of an image focal plane of the lens (2), is composed of a controlled light emitting element, and has a constant cross section defined by an illumination diaphragm. 2. The device according to claim 1, comprising an illuminating device (11) constituted by a light source for illuminating the) through the lens (2). 5. A translucent mirror (12) for displacing the illumination light source (11) away from the optical axis and allowing an analysis light beam emitted from the object (1) to pass therethrough. The device according to claim 4, comprising: 6. The illumination light source (11) is controlled by a microprocessor (7) according to a result of an analysis (6) of a signal (Si, j, φ) sent from the sensor (4). 5. The method according to claim 4, characterized in that it provides selective illumination in a given direction or according to a given illumination distribution, depending on the type of analysis performed on the object (1). apparatus.